Article of prism-glass.



1". L. 0. WADSWORTH. ARTICLE OF PRISM GLASS. APPLICATION FILED JAN. 23,1907.

Patented Jan. 24, 1911 wrruzs sss INVENTOR ms mmms PEYERS cm,WASHING70N, D c

UNITED STATES PATENT OFFICE.

FRANK L. O. WADSWORTH, OF PITTSBURG, PENNSYLVANIA, ASSIGNOR TO PRESSEDPRISM PLATE GLASS COMPANY, OF MORGANTOWN, \VES'I VIRGINIA, A CORPORA-TION OF WEST VIRGINIA.

ARTICLE OF PRISM-GLASS.

Specification of Letters Patent.

Patented Jan. 24, 1911.

Ilivided and this application filed January To all whom it may concern:

Be it known that I, FRANK L. O. Vans- \\'OII'I11,()f Pittsburg, in thecounty of Allegheny and State of Pennsylvania, have invented a new anduseful Article of Irisur Glass, of which the following is aspecification, reference being had to the accompanying drawings, formingpart of this specification, in which- Figure 1 is a vertical section ofa piece of prism glass embodying my invention; Fig. 2 illustrates indiagram the mode of operation of the glass; and Figs. 3, 4, 5 and (3 arerespectively sectional views showing n'updifications.

My invention provides a compound prism sheet of glass, in which theangular prism surfaces are not exposed on the exterior of the sheet.

The advantages derived from the invention are very great. As the angularprism surface is not exposed, the glass can easily be cleaned, and itpresents a much more sightly appearance than the prism-glass sheetsheretofore known.

The present application is a division of application Serial No. 291,397,filed December 12, 1905, and which issued as Patent No. 865,136, datedSeptember 3, 1907.

The invention is based upon.the principle, illustrated, in Fig. 2, thatif two bodies of glass of unequal density be fused together in intimatesurface contact the light rays will be refracted in passing from onebody to the other, or reflected by the surface of one of the bodies atthe plane of union according to the angle at which the rays impingethereon. This is illustrated in Fig.2, in which 2 and. 3 representbodies of glass of unequal densities and of different refractive indiceswelded or fused together. Rays of light a after passing through the body2 are refracted in passing rays 6 striking the plane of meeting of thetwo bodies at a less angle are reflected therefrom.

In the manufacture of prism glass in accordance with my invention, Iform a sheet of glass with a prismatic surface impressed thereon,employing preferably for that purpose the combined method of rolling andpressing described in Patent No. (361,025, granted to me conjointly withthrough the body 3, and

Daniel C. Ripley, and while the sheet so made is hot I roll upon it intoa sheet a second body of glass of different refractive index waich willfill up the cavities between the prismatic projections and willintimately unite therewith. Thus, referring to Fig. 1, I first roll amass of into a sheet 4;, and while the glass is still plastic I bringdown upon its surface a die having a prism pattern and impress the prismpattern upon the glass. Then, withdrawing the die, I cast upon the prismsurface of the sheet a second body of glass of different density, and bymeans of a roller I spread it ever the surface, filling the ridgesbetween the prisms and forming it into a second sheet 5. The compoundsheet may then be ground and polished. The manner in which the lightrays are refracted and reflected by such sheet is illustrated in thelines in Fig. 1. For the denser body of glass, or body having the higherrefractive index I may use a bariuin-lead-soda glass,.and for the lessdense body, or body having the lower refractive index a potash-limeglass. The proper composition of batch for such glass will be understoodby those skilled in the art.

In Fig. 3 I show a compound sheet which has been made in the mannerexplained above, and ground on each side to the plane of the apexes ofthe prisms.

In Fig. 1 I show a compound sheet of prism glass consisting, as before,of two sheets t and of different refractive indices with their prismsurfaces in intimate optical contact, but in which the sheet of lowerrefractive index is composed of other material than glass, such asCanada balsam, glycerin, etc. In this case a second flat sheet of glass6 may be added to protect the outer surface of the sheet of lowerrefractive index. This outer sheet of glass, however, has no effect onthe action of the compound prism sheet.

In Fig, 5 I show a compound sheet made as described with reference toFig. 1, but with prisms 6 and 7 of different form, and with the sheet ofglass of higher refractive index on the light receiving side. The sheetof Fig; 1 has the sheet of lower refractive index on the light-receivingside.

The sheet shown in Fig. 6 has the secondformed sheet 5 spread with agrooved roller which imparts a grooved or figured surface I of differentrefractive indices, and arranged to the sheet.

By the terms optical contact and contact as used herein and in theclaims, a contact is meant which is of a nature so close as to excludeany intervening medium of a different density from that of the glasssheets. The presence of any intervening substance, such as air, water orcement, would prevent optical contact, as that term is herein used.

Many other modifications may be made by those skilled in the art, sinceI claim 1. As a new article of manufacture, a compound prism sheetcomposed of sheets of transparent material of different refractiveindices formed with prism surfaces in contact throughout and weldedtogether; substantially as described.

As a new article of manufacture, a compound prism sheet composed ofsheets of glass of different refractive indices formed with prismsurfaces in contact throughout and welded together; substantially asdescribed.

3. A continuous transparent prism plate, composed of two series ofprismatic elements of different refractive indices, the surfaces of theprism elements of each series being in contact throughout and arrangedin nonparallel relation with the outer faces of the assembled structureso that the sets of prism elements produce a cumulative deflection inthe same direction of the transmitted rays of light; substantially asdescribed.

-'.l. A continuous transparent prism plate, composed of two series ofprismatic elements 1n non-parallel relation with the outer faces of theassembled structure so that the sets of prism elements produce acumulative deflection in the same direction of the transmitted rays oflight, the prismatic elements of one series being in contact throughoutwith the prismatic elements of the other series; substantially asdescribed.

5. A continuous transparent prism plate, composed of two series ofprismatic elements of different refractive indices, arranged innon-parallel relation with the outer faces of the assembled structure sothat the sets of prism elements produce a cumulative deflection in thesame direction of the transmitted rays of light, the prismatic elementsof one series filling the *avities between the other series and incontact throughout therewith; substantially as described.

6. A continuous transparent prism structure, composed of two series ofprismatic elements of different refractive densities i11- terfitted andin contact throughout with each other, the surfaces of the prismelements of each series being arranged in non-parallel relation with theother faces of the assembled structure, and the two series of prismelements producing a cumulative deflection in the same direction of thetransmitted rays of light; substantially as described.

In testimony whereof, I have hereunto set my hand.

F. L. O. \VADSVORTH. Vitnesses GEo. B. BLEMING, J OIIN MiLLER.

